by: John Bevan, DVM, DACVS-SA
Lucas, a 2 yr old MI German Shepherd, was presented for evaluation of trismus. Lucas was adopted at about 3 months of age and had been unable to open his mouth since then. Lucas could ingest gruel and water but was having significant exercise intolerance since he was unable to pant. On exam, the mandible could only be opened about an inch. Previous testing for masticatory myositis was normal. A CT scan (Fig 1) revealed a nonunion fracture of the right zygomatic bone with synostosis to the mandibular ramus. Anesthesia was performed via tracheal intubation. A portion of the zygomatic arch and the associated synostosis to the underlying ramus were removed (Fig 2). Surrounding fibrous and muscular adhesions were broken down. Mandibular ROM was about 90% normal immediately after surgery. The following afternoon, Lucas was able to eat canned food easily and was comfortable with mandibular ROM. At 2 weeks post-op, Lucas remained comfortable and his mandibular ROM was normal. At 6 weeks post-op, Lucas continued to do well. He was active, playful, and eating well. Mandibular ROM remained normal. No restrictions were reported by his owners.
Fig 1: 3D reconstructed images from pre-op CT scan
3D Reconstructed images from post-op CT scan
